X0306 4 2022-12-07 0 0001750019 TCR2 THERAPEUTICS INC. TCRR 0001556064 Menzel Garry E C/O TCR2 THERAPEUTICS 100 BINNEY STREET CAMBRIDGE MA 02142 1 1 0 0 President and CEO Common Stock 132729 I See Footnote Common Stock 132730 I See Footnote Common Stock 189234 D Common Stock 2022-12-07 4 S 0 9111 1.282 D 180123 D Common Stock 2022-12-08 4 S 0 9314 1.254 D 170809 D Consists of 132,729 shares of common stock held by the Garry E. Menzel Revocable Trust of 2022, under Indenture of Trust dated April 5, 2022 (the "Menzel Trust"). The reporting person is the trustee of the Menzel Trust, and as such the reporting person may be deemed to beneficially own such securities. The reporting person and members of his immediate family are the sole beneficiaries of the Menzel Trust. Consists of 132,730 shares of common stock held by and the Mary E. Henshall Revocable Trust of 2022, under Indenture of Trust dated April 5, 2022 (the "Henshall Trust"). The reporting person's spouse is the trustee of the Henshall Trust, and as such the reporting person may be deemed to beneficially own such securities. The reporting person and members of his immediate family are the sole beneficiaries of the Henshall Trust. The sales reported represent the number of shares required to be sold by the reporting person to cover tax withholding obligations in connection with the vesting of restricted stock units. These sales were automatic and intended to qualify under Rule 10b5-1. /s/ Margaret Siegel as Attorney-in-Fact 2022-12-09